I’ll be buying a sports-cat anyway as part of a full turbo-back Scorpion system and will be having a bespoke map done once fitted, along with a Wagner IC that I’ve already fitted myself. I have the option of not having the sports-cat actually fitted but leaving the straight-through front-pipe on, i.e. so it has no cat. The car will then be mapped accordingly and I can just swap the sport-cat on at MOT time. So cost is not an issue in this regards because I will have both the sports-cat and front-pipe at my disposal, my question is please what power/torque/drivability/noise differences will I feel between the two?? I don’t want it to be bad-boy loud but a little noise increase would be nice over the current standard system with centre-silencer removed (which made very little difference). Am I likely to hear an improvement with the new system and sport-cat? Would fitting the front-pipe (i.e. no cat) make it too loud/boomy??? Sorry for all the questions, and thanks in advance!
I think you'll find swapping the sports cat on and off at mot time, extremely difficult. It took the garage who done my decat about 3 or 4 hours to remove the original cat, and fit the decat.
The standard cat is attached to the turbo, removing this is the labour intensive part. Regardless of whether fitting a “de-cat” or a sports-cat the standard cat is replaced with a downpipe (AKA de-cat). The cat-back system is then connected to the downpipe with no cat having been fitted, or the front-pipe in the cat-back system can be exchanged for a sports-cat. So swapping a sport-cat on-off only means removing the front-pipe in the cat-back system, which I’m guessing will only take 10 minutes to remove and refit 6 bolts and the lambda sensor, if that.
Using a de-cat down pipe and swapping my current front pipe for a sports-cat version at that special time would be my ideal setup. Buying a proper sports-cat front pipe is so damn expensive though, especially if almost all of the time I wouldn't be using it. I'm hoping I can maybe do the same thing but just swap in a basic, generic, sports-cat when needed. I'm interested to hear if people think this would be worth doing over just mapping it to the sports-cat that you have and keeping it on all the time.
I have a scorpion decat and non res cat back fitted to my car, it's not really that loud at all. A bit more than a mid box chop but not as much as a mid box chop with a decat.
The Scorpion sports-cat front pipe is RRP £499, I’m being charged £410 fitted though so a little better but still like you say still expensive. The front-pipe as far as I can tell is straight therefore you may be able to fit a generic sports-cat but presumably the cost difference will be small over the one designed for your system. The little research I’ve done so far on the global-interwebulator seems to suggest that on a circa 300 bhp car the difference between a de-cat and a sports-cat may only be literally 1 or 2 hp, therefore indistinguishable between each other. Obviously fitting the sports-cat from the start though and the car being mapped to allow for this would be the far easiest thing to do, especially if the loss is only 1 or 2 hp.
Thanks, not sure if I read that properly though – so you have a Scorpion decat/down-pipe and then the non-resonated cat-back system (i.e. with just the single back-box) and you are saying this is only a bit louder than the standard system with the mid box chop but with the standard cat? I’m not arguing for one minute, just intrigued as the standard system is 2.5” and has the restrictive standard cat. But the Scorpion cat-less 3” system is only a bit louder? – I assumed it would be much louder…. You effectively have a mid-box chop with a decat system though. The non-resonated system basically doesn’t have the mid-box, the resonated version does. The standard 2.5” mid-box chopped system with a de-cat won’t be louder than a 3” non-resonated non-cat system, unless the standard back box is much smaller than the Scorpion, which I don’t think it is.
I've heard from Engine Dynamics: "I’ve not mapped one with the sports cat in as yet, so I’m unable to provide any firm pros or cons. It’s always been a clear cut of stage 1 with the cat or Stage 2 without the cat. One negative with any cat is heat, we have to run a slightly richer fuel mixture in the upper rpm to help control the cat temperature, this can dent the top end performance marginally.” So I guess it’s just what the difference between a sports-cat and a “de-cat” is???
The scorpion non res cat back with a decat isn't as loud as a mid box chop with a decat. I've had both
Thanks. Really, wow, I wouldn't have expected that. It must be down then to the Scorpion rear box being quieter than the standard box then, because otherwise they are almost identical systems.
I am actually doing the same set up. Already have a scorpion cat back non resonated. My scorpion decat and front link sports cat just arrived this afternoon. I have found a garage that will fit it for £225. Then it should be a simple half hour swap on the driveway between sports cat and a decat Sent from my iPhone using Tapatalk
The spec of your sports CAT can make quite a big difference to performance, as well as it's location. We can provide large body sports cats which flow far better than most other but still retain 200 CPSI and provide good emissions results, although generally speaking a standard 4" body sports cat will flow enough for most peoples applications. Get in touch if you want any more info info@cgrautomotive.co.uk 01709 530871 www.facebook.com/cgrautomotive
Thanks mate, would be really interested to hear your thoughts on the noise difference between the standard system then the scorpion cat-back and then the full cat-less system once you get the new pipes fitted. Did you by any chance chop the centre-box on your standard system? I'm not having mine fitted for a couple of weeks so I still have the option for to go no-cat or sports-cat, just comes down to the sound for me.
RS250, have you fitted the decat and sports-cat yet? What difference did it make to the sound? Presumably you just had the standard cat on before?
Not yet. It's booked in for Friday. I did after first year of ownership went for the mid box chop and it was only slightly louder on normal driving, nothing extreme or boy racer type. In sports mode it would pop and crackle. Then I decided on a scorpion cat back system so had that fitted and it sounded much better. It pop and crackle in normal mode then when it is in sports mode it would be louder still with its original cat. So the plan is on Friday have the sports cat fitted and leave it on for a while probably until May when it's due it's MOT. Then remove the sports cat if I find it not loud enough for my ears. Sent from my iPhone using Tapatalk
I'm having a sports cat (old KTEC one after turbo) fitted next month and then mapped after that. Interesting what CGR say and ED about the heat being a restriction. So sports cat and map won't be as good as decat and map then? But a lot better than std cat and map surely?
Basically the further back in the system you fit a CAT, the more power you can make, but the lower the temperature in the cat the less likely it is to pass an emissions test and actually work, so fit it too far back and it's essentially pointless being there as it's causing a restriction without actually doing its job! But yes a sports cat and map will make more power than the factory cat, but not as much as a decat, in theory
Thanks RS250 and everyone, I think I've made up my mind to fit the SC from the go and have it mapped accordingly. From what I've seen on other car forums on a circa 300bhp car a SC will only loose a couple of BHP over going non-cat. And then there's the hassle of having to swap it over at MOT time and also non-cat may be a bit too noisy and also for when I eventually take it on track.
I'd be surprised if even full decat the Meg would fail noise tests, maybe fly bys? But even then the fact there's a turbo in the pipe work silences a lot of noise. Have seen Clios with full straight through pipes pass noise tests I like the idea of moving the cat a bit further down and making it a bit bigger but my understanding of newer MOT regs was that cats have to be in the same place as factory? Though how or if any MOT station enforces that I'm not sure.
My local track has a 95db limit and I get a black flag if I don't lift at one measuring point. The other 2 points are fine. 275 with just a decat. 95,8 - 97db..
With what exhaust? Ive got a ktec 3" catback And its isnt much louder than stock really (in the car anyway) and mate has same with decat and its no different to mine really
Had the scorpion sports cat fitted. The sound is awesome, just right for my taste. I will wait to see if the engine management lights comes on in two week times, it shouldn't but you never know. Pops and crackle perfectly without being in sports mode. So far I love it. Sent from my iPhone using Tapatalk
Got a video now on YouTube. Link below: Normal mode then sports mode then back to normal. Sent from my iPhone using Tapatalk
That sounds perfect, just the right level and raspyness rather than boom. So just to confirm, its the full Scorpion turbo-back system with the Scorpion sports-cat? (Basically like I'm going to getting)
This, the Megane isn't that loud even with a decat IIRC mine was only 89db last time it was tested. That's with a stock system with midbox removed which is supposedly louder than a full 3" system
I have a CGR decat on the way and have been thinking about getting a custom straight through from the downpipe back to the stock back box - is 2.75" or 3" generally the best size ?
I have a custom 3" catback exhaust, I also have a a CGR decat, however I still have a bit of the old pipe left, so that part is 2.5" I think. Most people go for 3" I think.
